Aircraft construction



Dec. 28, 1937. H. G. KLEMM ET AL AIRCRAFT CONSTRUCTION Filed Dec. 29, 1936 2 Sheets-Sheet l n8 1 11 l I INVENTOR. HERMAN G.K LEMM B ERTHOUD C. BOU LTON ATTORNEY.

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H. G. KLEMM ET AL AIRCRAFT CONSTRUCTION 2v MN O NO E m ET, N e A L R h E LU O 6 w o T m m a n. m NC A S D M 2 RW R I E B 6 Y B l o o l lw nl 9 2 I! v c fN e w 0 an 1 i F n O H rm 3. vW WWMwwMWMw V wm u w M/ fi d o m o m mw o s s 6 oh Dec. 28, 1937.-

Patented Dec. 28, 1937 PATENT OFFICE AIRCRAFT CONSTRUCTION Herman G. Klemm, Baltimore, and Berthoud C.

Boulton, Towson, Md., assignors to The Glen L. Martin Company, Baltimore, Md.

Application December 29, 1936, Serial No. 118,072

7 Claims (01. 244-53) This invention 'relates to an aircraft construction and more particularly to an improved method and apparatus for. dissipating the exhaust gases from an aircraft engine.

It has heretoforebeen the general practice to extend the exhaust outlet externally of the aircraft surfaces where the exhaust gases expand for the greater part within the airstream surrounding the surfaces of the aircraft. These protrusions are not only undesirable because of the turbulence produced by their interference with the air-stream, but the expansion of the exhaust gases as well as the velocity and temperature thereof also act to set up additional air disturbances which impair the efliciency of the aerodynamic feature of the aircraft surfaces adjacent to the exhaust outlet or outlets.

It is one object of this invention to provide an improved method and apparatus for overcoming the above difficulties.

Another object is to provide an improved method and apparatus that shall operate to dissipate the exhaust gases of an aircraft engine externally of the aircraft surfaces in such a manner as will obviate objectionable disturbances to the airstream. v Another object is to provide an improved method and apparatus that shall initially accommodate the exhaust gases flowing from an exhaust silencer of an aircraft engine within the surfaces of the aircraft.

Another object is to provide an improved method and apparatus having the above characteristics that shall include a novel means for expanding the exhaust gases as. well as reducing the velocity and temperature thereof within the confines of the aircraft surfaces and subsequently releasing such gases to the surrounding medium of the aircraft.

A further object is to provide a method and apparatus having the above characteristics that shall expand the exhaust gases as well as reduce the velocity and-temperature thereof in definite steps and release such gases to the surrounding medium at fairing regions of the aircraft surfaces and at points of negative aerodynamic pressures. I

A still further object is to prepare a method and apparatus having the above characteristics that shall include novel means for supplying air to the intake of an engine carburetor at predetermined temperatures.

The above and other objects will be made apparent throughout further description of the invention when taken in connection with the accompanying drawings wherein like reference characters refer to like parts. It is to be distinctly understood that the drawings are not a definition of the invention, but illustrate certain forms by means of which the invention may be effectuated. The invention will be defined by the scope of the appended claims.

In the drawings:

Figure 1 is a fragmentary plan view of an aircraft of the bi-motored monoplane type illustrating one embodiment of the invention.

Figure 2 is a sectional viewtaken along the line 2-2 of Figure 1.

Figure 3 is an enlarged detail view embodying the invention. 5

Figure 4 is an enlarged detail sectional view similar to Figure 2 illustrating another embodiment of the invention.

Figure 5. is a fragmentary top plan view of Figure 4.

Figurefi is an enlarged sectional view taken along the line 6-6 of Figure 4', and Figure 7 is a diagrammatic view of a control arrangement embodying the invention.

The present invention is illustrated and described in connection with an aircraft of the bimotored monoplane type. However, it is to be understood that the invention is equally adaptable for use with other types of aircraft.

Referring to the drawings, Figures 1, 2, and 3 illustrate one embodiment of the invention wherein l0 indicates an aircraft fuselage mounted on or having laterally extending from the sides thereof a wing H and a powerplant represented in its entiretyby i2 positioned on each side of the fuselage i0 and supported by the structure of the wing i I. The power plant which includes the engine i3 is provided with exhaust means represented in its entirety by H, and a carburetor intake i5. In the form shown, the 40 engine i3 is of the radial type and mounted within a ring cowling IS, the rear edge of which is adapted to cooperate with the forward portion of a nacelle body I1 and defining an annular opening l8 therebetween. The ring cowling i6 45 is provided with the usual opening I! in the front thereof for supplying cooling air to the cooling system of the power plant.

The exhaust means ll here employed comprises an exhaust ring 2|, the latter being operably con- 5 nected with the exhaust of each of the radially disposed engine cylinders by means of pipes 22. Extending rearwardly of the exhaust ring is an exhaust pipe 23 which may be a continuation of i the exhaust ring 2| and is employed for connect- 5 ing the exhaust ring 2| with an exhaust silencer represented in its entirety by 24. The exhaust silencer 25 is located, within a compartment 25 provided in the fairing region of the wing II.

This compartment 25' which includes a perforated or slotted top 25 is preferably constructed so that the'entire compartment may be bodily reregulating the amount of air entering the ppening 51 in the forward portion of the wing I for con-' trolling the cooling of the compartment 25 as.

moved from the aircraft. This is important in that the compartment is adapted for readily cleaning, inspecting, repairing and replacing.

The entrance of the pipe 23 is preferably provided with suitable means such as shown at 28 for sealing the interior of the compartment 25 against any egress of gases into that portion of the wing body forward of the compartment 25.

Novel means is provided for cooling the compartment 25 which consists of the provision of a compartment surrounding the compartment 25. This compartment 55 is supplied with cooling air by way of an air duct 56 connecting an opening 51 disposed in the forward portion of the wing H. The air passing through the air duct 56 and into the compartment 55 is expelled in the fairing region of the wing through openings 58. This compartment 55 serves to cool the compartment 25 as well as to provide an air insulating means between the compartment 25 and the adjacent surfaces of the aircraft. The compartment 55 may be further provided with an asbestos insulation as shown at 21. The air duct may be provided with suitable valve control means, not shown, for

well as maintaining the drag through the air duct 55 and compartment 55 at a minimum.

Any number of mufliers or silencers 24 maybe employed in connection with the exhaust pipe 23 as shown at 23 (see Figure 1). Any suitable type of silencer 23 may be employed. However, it is desired that the velocity of the gases be reduced 2 as well as expanded and cooled prior to releasing them to the atmosphere. A novel silencer for accomplishing this purpose will later be described in connection with Figures 4 to 6 inclusive.

This particular construction provides a novel manner in which to supply heated air to the intake of the carburetor when such heated air is desired. This is accomplished by providing a manifold like covering or housing 3| for at least a portion of the length of the exhaust pipe 23 and thereby defining an air passageway 33 connecting the interior'of the engine cowling IS with the air passageway or opening 32 positioned within the fairing; region of the wing II. This particular region being at a point where the aerodynamic pressure is negative effects a suction by way of the opening 32 from the housing 3| and operates to draw air from the cooling system supplied through the opening l3, 'engi'ne'cowling l3, into the forward end of the housing 3| as indicated by "the arrow 33, through the housing 3| and operating to absorb heat from the exhaust pipe 23. At

some selected point mm housing 3| there is provided an air duct 34 connecting the interior of the housing 3| withan air Sam]: 35, the latter being provided with suitable controls 35 which may be operated either bythe pilot, or by automatic means, for scooping up air and inducing it "mt th housing 3| and directing it in the direc tion indicated by the arrow 33'. I

In order to effectively accomplish this operation, the opening 32 is provided with suitable means such as shown at 31 (see Figure 2) for closing the opening 32 and eliminating any auction therethrough also a suitable connection, such-- as an air duct, 38 is provided for connecting the forward end or'the interior of the housing 3| with the intake of the carburetor l5. Any suitable means may be employed for connecting or disconnecting the intake of the carburetor, l5 with the air duct33. Therefore, it follows thatwhen the opening 32 is closed that the scoop35 will direct air through the air duct 34 forwardly through the housing 3|, through the air duct 33, and into the intake |5 of the engine carburetor and that during the passage of air through the exhaust housing'll it will absorb heat from the exhaust pipe 23 to a intake of the carburetor with either a supply of cold air or hot air. When it is desired to supply hot air to the intake of the carburetor l5, it is desirable to close the opening 32 by the means 31 and open the air scoop 35 as well asclose the entrance of the cooling air into the forward end of the housing 3|. Figure 7 illustrates a control system whereby a single actuating handle 53 may be employed for simultaneously operating the valves 5| and 52, scoop 35, means 31, and a valve 54 positioned within and adapted to close the mouth or forward end of the housingjl. As illustrated in Figures 2 and! the several controls are in the position for supplying heated air to the intake of the carburetor l5, the scoop :5 being open while the opening 32 in the fairing region of the wing II is closed as well as the forward end of the housing 3| by'the valve5l. Thispermits air to pass by way of the scoop35, through the air duct 34, through housing 3|, air'duct-33,.and.into the'intake of the carburetor l5. It .tvillbnoted thatjiif theiactuating handle 53 is movedjto the left as viewed in Figure '7 that the sev'eraloon'trol connections will be operated to simultaneously close and open the valves52 and 5| respectively and also simultaneously close scoop 35 and open theopening 32 and valve-53 the mouth of the'forward end of the housing 3|.

Figures 41 and 5 illustrate another embodiment of the invention wherein the compartment 25 is located in the fairing vregion of nacelle l1. The exhaust pipe 23 inthisenibodiment, while shorter than that described above, is also supplied with a housing 3| communipating with the interior of an annularly shaped housing 35 disposed about the exhaust ring 2|. The fairing'of the nacelle I1 is also provided with opening-32 connecting the interior of the housing 3| with the exterior of the nacelle surface. The cooling air for the exhaust pipe 23 is supplied through tube like con nections 3| surrounding exhaust P pes 32 and connecting the interior of the hbusing 33 with the interior of the engine cowling l5. Cooling air enters the tube like members 4| as indicated by the arrows 42 (see Figure 4), passes into the housing 33, and out through the opening 32 by way of the housing 3|.

This embodiment includes an improved mufller -or silencer for expanding and reducing the velocity and temperature of the exhaust genes. In

of velocity and temperature.

each of the silencers u (see Figure 6) the exhaust gases initially enter an inner cylinder 44, the latter having perforations on its upper surface as shown at for permitting the gases to pass into a second cylinder 46, this cylinder having perforations on its lower surface as shown at 41 for permitting the gases to pass into the compartment 25 for further expansion and reduction These. gases are subsequently freed to pass out through the'perforated or slotted top 26 of the compartment 25. Any number of cylinders may be employed. However, it is desired that the respective openings such as 45 and 41 be positioned on opposite sides of the adjacent cylinders in order that the gases will be directed around'the cylinders prior to entering the surrounding'cylinders or compart ment 25.

Accordingly, I have provided in an improvedaircraft construction a novel method and apparatus wherein the exhaust silenceris accommodated within the aircraft surface in such a manner as to obviate the undesirable feature of having the exhaust outlets extending externally of the aircraft surface; novel means for expanding the exhaust gases as well as reducing the velocity and temperature thereof which operate to further eliminate air disturbances due to the expansion, velocity, and temperature of such gases; a novel construction, an arrangement of an exhaust compartment positioned within the fairing region of the airfoil sections of an aircraft that will permit the release of these gases at points where the aerodynamic pressure, relative to the aircraft surface, is comparatively small and negative in nature; also the present construction provides an exhaust compartment that may be readily removed from the aircraft for cleaning, inspecting, and repairing. All of the above mentioned features operate to obviate air disturbances usually set up due to the direct releasing ofexhaust gases within or adjacent to the air streamassociated with the aircraft surfaces.

While .I have illustrated and described this invention in connection with a bi-motored monoplane it will now be apparent to those skilled in the art that the present invention is equally adapted for the use with a single motored plane and that the exhaust compartment as well as the particular type of silencer used may be positioned at various locations within the aircraft surfaces and still utilize the teachings of thisinvention and that other changes, modifications, substitutions, additions, and omissions may be made in the structures here illustrated and described without departing from the spirit and scope of the appended claims.

We claim:

1. In an aircraft having high and low pressure areas enveloping the surfaces thereof and having means producing hot exhaust gases, means to exhaust saidgases at a surface portion of said aircraft into a low pressure area, and means to produce a flow of cooler gases from within said surfaces into said low pressure area between said means to exhaust said gases and the adjacent portions of said aircraft surfaces.

2. In an aircraft as in claim 1, means to place said cooler gases in heat exchange relation with said exhaust gas within said surfaces of said aircraft.

3. In an exhaust system for aircraft an exhaust chamber located within and communicating with a perforate portion of the surface for said aircraft, a cooling compartment partially enclosing and sealed from said chamber, means to introduce a cooling medium into said compartment, and means exhausting said cooling medium throughsaid surface into a cooling area between said perforate portion and an imperforate portion of said surface. v

4. In an exhaust system as in claim 3, said introducing means comprising an air duct extending from said compartment, and said exhausting means comprising another perforate portion of said covering. 5. In an exhaust system as in claim 3, an engine, an exhaust pipe connecting said engine and said chamber, and a cooling jacket surrounding and spaced from said pipe, said jacket being contained substantially entirely within the surface of said aircraft.

6. In combination with an aircraft, a receptacle having a perforate side and imperforate other sides, said perforate side being composed of a surface portion of said aircraft, a muffler in said receptacle, a compartment sealed, spaced from, and partially enclosing said receptacle, said compartment having a perforate wall and imperiorate other walls, said perforate wall of said compartment forming a part of the surface of said aircraft which lies between said perforate side of said receptacle and the adjacent surfaces of said aircraft, and means to circulate a cooling medium through said chamber. 7

'7. In the combination of claim 6, said perforate side of said compartment comprising a surface portion of said aircraft surrounding said perforate side of said receptacle. 

